Known in the past have been certain metal ore extractants for use in aqueous systems for removing metal values. The compounds, disclosed in U.S. Pat. Nos. 2,866,680 and 2,947,774, are certain dialkyl esters of diphosphoric acid wherein the alkyl moiety is the remnant of an alkanol. The references teach that the compounds rapidly decompose, most likely forming monophosphate esters.